The effect of marking, mulesing and dehorning on survival and growth of Merino lambs.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. I9 THE EFFECT OF MARKING, MULESING AND DEHORNING ON SURVIVAL AND GROWTH OF MERINO LAMBS R. P. THOMPSON, N. MURRAY and D.. J. MOORE Dept of Primary Industry Tasmania, Scottsdale, Tas. 7260. Some properties in north east Tasmania reported high (20%) lamb mortalities between marking and weaning. Trauma induced by marking and mulesing was suggested as being reponsible. Three hundred and ninety-two 4 to 6 week old Merino ram lambs born in September 1990 at Rushy Lagoon near Gladstone Tasmania were randomly allocated to 4 groups. The basic design was a 2 x 2 factorial consisting of 2 mulesing treatments (mulesed or not mulesed) and 2 castration treatments (knife or ring). In addition 20 from each treatment group of 98 were then dehorned using calf scoops. Liveweight gain and survival were measured between lamb marking and weaning (66 days). All castration, mulesing and dehorning wounds had healed by this time. Fly strike of the wounds was not a problem. The results were analysed using analysis of variance. Table 1 shows the mean growth rates and survival of the lambs over the treatment period. None of the imposed treatments significantly (P > 0.05) depressed growth rate or survival. Interactions of the mulesing and marking treatments with dehorning were not significant (P > 0.05). Rose et al. (1972) reported that mulesing depressed growth rate for the lo-day period subsequent to the operation. However, their findings agree with those of this experiment that 9 weeks post operation there is no effect of mulesing on lamb liveweight. Lear et al. (1974), as in the present experiment, found no difference in weight gain or survival of fine wool Merino lambs castrated surgically or with rubber rings. However, perhaps surgical rather than ring castration and docking should be favoured on welfare grounds as it has been demonstrated to cause less distress (Shutt et al. 1988). Table 1. Growth rate and survival of homed or dehorned lambs castrated surgically (knife) or with a rubber ring, and mulesed or not muelsed, mulesed and dehorned The results reported here suggest dehorning done in conjunction with mulesing does not affect growth and survival. Dun (1963) reported dehorning ram lambs but not in conjunction with castration or mulesing. The surgical technique was labour intensive using modified boot makers pincers. Even though Dun performed the operation on lambs ranging from 2-8 days old post treatment death was not increased by the procedure. The procedure resulted in the growth of short (100-150 mm) horns without a bone core, these were easily removed. Horn regrowth was not evident on the wethers in the present experiment. Dehorning wetheis at marking may reduce handling problems and bruising. Further work is being conducted using ram lambs. The results suggest the high lamb mortalities were not associated with castration and mulesing procedures. DUN, R. B. (1963). Aust. J. Exp. Agric. Anim. Hush. 3: 266-8. LEAR, D. M., O' BRIEN, S. J. and GLASSFORD, J. J. (1974). Proc. Aust. Sot. Anim. Prod. 10: 3724. ROSE, M., McMENIMAN, N. F? and ANSON, R. J. (1972). QZd J. Agric. and Anim. Sci. 29: l-7. SHU' D. A., FELL, L. R., CONNELL, R. and BELL, A. K. (1988). Aust. Vet. J. 65 (1): 5-7. IT, 422